1. Field of the Invention
This invention relates to an attenuator for simultaneously providing attenuation in a plurality of external circuits and more particularly to an attenuator that can be utilizied to provide selectively either balanced or unbalanced attenuation in a plurality of external circuits.
2. Description of the Prior Art
In providing attenuation in electrical systems, such as, for example, when attenuation is required in transmission lines, it often becomes necessary to provide identical magnitudes as well as different magnitudes of attenuation to the respective transmission lines. A transmission system may be of either a balanced design, i.e., has equal currents flowing in each line of the transmission pair, or an unbalanced design, i.e., have unequal currents flowing in each line of the transmission pair. The transmission system design dictates the type of attenuation design required to adjust the transmission signals of the desired levels.
In prior art attenuator arrangements, balanced and unbalanced attenuation is provided in a given transmission system by utilizing attenuator structures which provide respective designated magnitudes of attenuation for that type transmission line design. Since individual attenuators are provided for each transmission line, the number of different attenuator structures that can be required for providing the balanced and unbalanced attenuation can be relatively large and expensive. Additionally, when providing balanced attenuation to the transmission lines, a problem can be created if care isn't taken to insure that the same magnitude of attenuation is provided in each of the respective transmission lines. Accordingly, it is desirable to provide an attenuator design concept which will minimize the number of different attenuator structures required in providing both balanced and unbalanced attenuation.